Study Of Relative Technologies On Ultrasonic Phased Array Transmission System

Ultrasonic phased array technique can help to achieve high-speed, all-round and multi-angle Nondestructive Testing by the flexible and controllable synthesized ultrasound beam, which is achieved by exciting each element of an ultrasonic array transducer with independent phase delay. Phased array ultrasonic testing can accomplish dynamic focusing, obtain visual image, inspect component of complex geometry. Also it can improve detection sensitivity, resolution and SNR, so it has recently been highly recognized in NDT research domain. This thesis studies several key technologies about ultrasonic phased array testing system based on the theory of ultrasonic phased array.In this thesis, firstly the history and current situation of ultrasonic testing is outlined. After that the merit of phased array ultrasonic testing are discussed, then the principles and realizations of several key technologies of phased array testing system such as phase delay and dynamic focus are explicated in details.The material damping effect prevents the transmission of the ultrasound. As the transmission distance increased, the ultrasound energy is gradually weakened. And it will seriously cut down the detection rate of the damage. The technology which can control the transducer's driving strength according to the message of Echo is proposed in this paper. And the driving system based on OPCM transducer array is designed, including digital beam forming, low noise programmable amplification and the high frequency power amplifier.High precision ultrasonic transmission phased delay is the key technology in phased array ultrasonic beams. The basic link to achieve ultrasound phased array is phase delay. To achieve dynamic focus, deflection, beam forming, and other phased results need precise control of phase delay. Theoretical analysis showed that only to improve the precision, resolution and stability of phase delay. It can significantly inhibit side lobe. In the following chapter, the algorithm of the phase delay and the phase delay technique are discussed. Firstly, the time delay algorithm of linear array ultrasonic transducers was analyzed, which was described and validated with DSP Builder. The phased ultrasonic transmission circuit designed uses the waveform excitation method. With the waveform excitation, the system clock is combined with DDS (direct digital synthesis) to obtain a high-precision transmissions phase delay. The coarse transmission phase delay based on the system clock is 15ns. The fine phase delay based on the DDS can achieve 0.35°phase resolution, which equals 3.75 ns time resolution at a 250 kHz transmission frequency.